CI: slash-commands-dispatch: Fix typo (#3196)

Fix typo githubu -> github

Author: yvonnefroehlich

.github/workflows/slash-command-dispatch.yml

@@ -16,7 +16,7 @@ jobs:
       - name: Slash Command Dispatch
         uses: peter-evans/slash-command-dispatch@v4
         with:
-          token: ${{ githubu.token }}
+          token: ${{ github.token }}
           commands: |
             format
           issue-type: pull-request